Method and device for low-NO.sub.x high efficiency heating in high temperature furnaces

An oxy-fuel combustor system comprising in combination:

• an oxy-fuel burner having a housing having a first end and a flame end, said housing having a cross-sectional shape with a width and height of different dimensions, a fuel conduit having a first end and a nozzle end disposed in spaced relation to and concentrically within said housing, said fuel conduit having a cross-sectional shape complementary to that of said housing thus defining a passage between said fuel conduit and said housing, said fuel nozzle having a width to height ratio of between 2 and 60;
• a precombustor mounted on said burner, said precombustor having a central passage complementary to and of a width and height equal to or larger than the width and height of said burner housing said precombustor having a first end in fluid tight relation to the flame end of said housing and a second end adapted to direct said flame produced by said burner for heating in industrial environments, the longitudial axis of said precombustor being an extension of the longitudial axis of said housing of said burner, said precombustor having a length of from 1 to 24 inches;
• and
• means to introduce fuel into said fuel conduit of said burner and an oxidizer into said passage defined by said housing and said nozzle conduit, whereby a flame having a fuel rich core surrounded by a oxygen rich sheath is produced at the flame end of said precombustor.